def f(n):
    d=2
    while d*d<=n:
        if n%d==0:
            return False
        d+=1
    return True
d=['zero','one','two','three','four','five','six','seven','eight','nine']
a=input().split()
if len(a)!=3 or a[0] not in d or a[1] not in d or a[2] not in d:
    print("Wrong input")
else: 
    n=int(str(d.index(a[0])) + str(d.index(a[1])) + str(d.index(a[2])))
for i in range(1,1000):
    if f(n-i):
        print(n-i)
        break
    if f(n+i):
        print(n+i)
        break